Wireless personal area networks (WPANs) provide wireless short-range connectivity for electronic devices such as audio/video devices within a home. The Institute of Electrical and Electronics Engineers (IEEE) 802.15 High Rate Alternative PHY Task Group (TG3a) for WPAN is working to develop a higher speed physical (PHY) layer enhancement to IEEE proposed standard P802.15.3™—Draft Standard for Telecommunications and Information Exchange Between Systems (referred to herein as the proposed IEEE standard). Presently, Ultra Wideband (UWB) technology is under consideration by the Institute of Electrical and Electronic Engineers (IEEE) as an alternative physical layer technology. UWB technology, in general, uses base-band pulses of very short duration to spread the energy of transmitted signals very thinly from near zero to several GHz.
In particular, Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) has been proposed for the IEEE standard due to its spectrally efficiency, inherent robustness against narrowband interference, and robustness to multi-path fading, which allows a receiver to capture multi-path energy more efficiently. The inverse fast Fourier transform/fast Fourier transform (IFFT/FFT) operation ensures that sub-carriers do not interfere with each other. OFDM signals have very good in-band and stop-band performance because they have generally flat power spectral density (PSD) in-band and a sharp cut off in the stop-band.
In MB-OFDM, the UWB frequency spectrum, which covers 7.5 GHz in the 3.1 GHz to 10.6 GHz frequency band, is divided into 14 bands, each occupying 528 MHz of bandwidth. Each band includes 128 sub-carriers of 4 MHz bandwidth each. Information is transmitted using OFDM modulation on each band. MB-OFDM may use coding such that information bits are interleaved across various bands to exploit frequency diversity and provide robustness against multi-path interference. MB-OFDM, however, does not offer sufficient frequency diversity for higher code rates (i.e., low redundancies). Typical techniques to increase frequency diversity in MB-OFDM systems, however, often have a relatively high level of complexity, which adds to the cost of implementing such techniques.